This invention relates to a compact utility loader which has a traction system and is guided by an operator who walks behind the loader. More particularly, this invention relates to a control system for controlling the operation of the traction system.
U.S. Pat. No. 5,423,654 to Rohrbaugh discloses a tracked, walk-behind loader for use in the coal mining industry. The loader includes a rotary turntable which mounts an extensible boom. An attachment, such as a bucket, is pivotally mounted on the front of the boom. The boom can be swung about a vertical axis by virtue of the turntable. In addition, the boom can be pivoted about a horizontal axis to vary its angle of inclination relative to the ground, the boom can be telescoped and retracted to vary the boom""s length, and the attachment on the front of the boom can be tilted relative to the boom.
A single control handle is used in the Rohrbaugh loader to control the tracked traction system. This control handle can be pushed forwardly or pulled rearwardly to drive the loader in forward and reverse. To steer or turn the loader, the control handle is rotated or twisted from side to side.
While such a control handle is effective, it can be tiring for the operator to use. For example, keeping the handle pushed forwardly, or keeping it rotated to the side, puts strain on the handle and the muscles of the lower arm. Accordingly, while having a single control handle is desirable for the sake of control simplicity, the strain involved in keeping it in an actuated position quickly tires the operator.
Moreover, the task of keeping the control handle in a desired position is complicated in a loader in which the operator walks behind the loader and is not carried by the loader. Since loaders of this type are apt to be operated on uneven, tilting terrain, the operator who is following the loader will encounter situations where the loader moves onto terrain that is at a different slope or tilt than the terrain on which the operator is standing. For example, the loader might move onto terrain that is steeply sloped to one side while the operator is still located on much flatter terrain. Thus, it will be common for the loader to tilt or pivot, both fore-and-aft as well as side-to-side, relative to the trailing operator. The only physical connection between the loader and the operator are the operator""s hands placed on the controls of the loader.
The movement of the loader relative to the operator complicates the task of keeping the traction control handle in a desired position. For example, if the loader suddenly tilts to the side relative to the operator, the operator""s hand placed on the control handle must necessarily follow this sudden movement. This sudden movement of the loader will often cause the operator""s hand to inadvertently and unintentionally move the control handle out of its desired position, thereby initiating an unintended turn or perhaps unintentionally causing the loader to speed up or slow down as the case may be. Thus, using a single control handle as in Rohrbaugh, without some reference point to grab onto, will often cause the loader to be driven in a jerky, abrupt fashion. This is particularly true when the operator is not highly skilled or experienced in using the control handle to control movement of the loader.
In addition, from a safety and operational standpoint, it is desirable that the control handle be returned to neutral when the operator releases the handle. This return to neutral should happen for both types of motion of the control handle, for both the fore-and-aft pushing or pulling motion and the side-to-side twisting motion. This is difficult to achieve in an efficient manner. Thus, while some controls might return to neutral with respect to the pushing or pulling motion, these same controls-might not return to neutral with respect to the twisting motion.
In Rohrbaugh, no return to neutral is disclosed for the control handle. Thus, if the control handle remains wherever it is set by the operator, which would obviously ease the effort needed by the operator to hold the control handle, the loader would continue moving if the operator were to release the control handle. This is not desirable. Thus, there is a need in the art for a control handle which reliably returns to neutral with respect to any motion that is imparted to the control handle, which can be moved and held by the operator in an advanced position with as little effort as possible, and which allows the operator to smoothly control the operation of the traction system even though the operator walks behind the loader during operation of the loader.
One aspect of this invention relates to an outdoor equipment unit which comprises a frame. A ground grooming or working attachment is carried on the frame. A source of power is carried on the frame. A traction system is carried on the frame for propelling the frame in forward and reverse directions and for steering or turning the frame during motion of the frame in forward and reverse directions, the traction system being powered by the power source. A control system is provided for operating the traction system. The control system comprises a control handle that is pivotal about a first pivot axis and is rotatable about a second pivot axis that is perpendicular to the first pivot axis. The control handle is operatively coupled to the traction system such that pivoting of the control handle about the first pivot axis causes motion of the frame in forward and reverse directions while rotation of the control handle about the second pivot axis steers or turns the frame during motion of the frame in forward and reverse directions. A first return to neutral system including at least one first return spring is provided for returning the control handle to neutral with respect to pivoting about the first pivot axis. A second return to neutral system including at least one second return spring is provided for returning the control handle to neutral with respect to rotation about the second pivot axis. The second return to neutral system including the at least one second return spring is carried by the control handle to move with the control handle as the control handle pivots about the first pivot axis, whereby the second return to neutral system is effective to straighten the frame out following a turn once the rotation of the control handle with respect to the second pivot axis is released even when the frame is still being driven in a forward or reverse direction with the control handle still being held in an out of neutral position with respect to pivoting about the first pivot axis.
Another aspect of this invention relates to an outdoor equipment unit which comprises a frame. A ground grooming or working attachment is carried on the frame. A source of power is carried on the frame. A traction system is carried on the frame for propelling the frame in forward and reverse directions. The traction system is powered by the power source. The traction system includes separate left and right drive motors for powering left and right ground engaging drive members carried on opposite sides of the frame. A control system is provided for operating the traction system The control system comprises a control handle, first and second linkages for controlling the first and second drive motors; and a control shaft which is elongated to extend along a control shaft axis, the control handle being fixed to the control shaft and the linkages being coupled to the control shaft in positions which are offset to either side of the control shaft axis. A bushing member is pivotally secured to the frame for rotation about a substantially horizontal pivot axis, the control shaft passing through the bushing member such that the bushing member pivotally journals the control shaft on the frame for fore-and-aft pivoting about the substantially horizontal axis to pull or push on the linkages, respectively, to control the ground speed of the frame in forward and reverse directions, respectively. The control shaft is further rotatable to one side or the other within the bushing member about the control shaft axis for pushing or pulling on the linkages unequally to turn the frame out of a straight line path.
Yet another aspect of this invention relates to an outdoor equipment unit which comprises a frame. A ground grooming or working attachment is carried on the frame. A source of power is carried on the frame. A traction system is carried on the frame for propelling the frame in forward and reverse directions, the traction system being powered by the power source. A control system is provided for operating the traction system. The control system comprises a movable control handle that is pivotally journalled on the frame for pivoting about at least a first substantially horizontal axis to control the ground speed of the frame in forward and reverse directions. The control system also comprises a grab bar assembly fixed to the frame for use with the control handle to provide a reference which the operator can grip simultaneously with the control handle to help the operator keep the position of the control handle relatively constant. The control handle and the grab bar assembly provide three spaced, generally parallel members including a front member, a rear member, and an intermediate member placed between the front and rear members. The front and rear members form one of the control handle and the grab bar assembly and the intermediate member forms the other of the control handle and the grab bar assembly.